The Diagonale des Fous: Everything You Need to Know About the Grand Raid of La Réunion

From the volcano to the cirques, from primary forests to wind-swept ridges, this grand raid pushes the limits of what the body and mind can endure. Here’s everything you need to know about this extraordinary challenge.

What is the Diagonale des Fous and why is it so legendary?

The Diagonale des Fous, also known as the Grand Raid de La Réunion, is an ultra-trail crossing the volcanic island of La Réunion from south to north. The start is in Saint-Pierre, at Ravine-Blanche, and the finish is in Saint-Denis, at the Stade de la Redoute. In between, a route of rare intensity: kilometers of technical trails, dizzying elevation gain, abrasive volcanic terrain, dense tropical forests, and cirques classified as UNESCO World Heritage sites.

The Diagonale des Fous is renowned for this unique combination of factors. Nowhere else in the trail running world will you find such a variety of terrains condensed into a single race. The tropical heat of the lower sections gives way to the biting cold of the peaks. Earthen trails give way to irregular lava steps, slippery roots, and muddy passages where every footing demands total concentration. Weather conditions are never predictable: torrential rain, thick fog, violent winds on the ridges... La Réunion always delivers surprises.

It’s this unpredictability, this absolute challenge, that has built its legend. Finishing the Diagonale des Fous means joining a special community. Those who dared, who suffered, who endured. The famous "I survived" t-shirt you receive at the finish is not just a souvenir. It’s a badge of belonging.

What is the course of the Diagonale des Fous?

The route of the Diagonale des Fous changes from year to year, but its spirit remains the same: cross the island from end to end, taking the most demanding, beautiful, and formidable trails. The current course stretches about 180 km with an elevation gain of over 10,000 meters, making it one of the longest editions in Grand Raid history.

The start in Saint-Pierre immediately immerses runners in the heart of the challenge. The first hours unfold in darkness, headlamp on, with steep climbs towards the Piton de la Fournaise massif, one of the world’s most active volcanoes. The terrain is a stark reminder of exactly where you are.

Next comes the crossing through the cirque of Mafate, one of the most remote places in France. Accessible only on foot or by helicopter, this natural cirque offers breathtaking scenery, but also imposes incredibly technical trails. Roche Plate, Grand Place, Roche Ancrée... each place is a checkpoint in an epic story. The Maïdo, marking the exit from Mafate, is one of the race’s most anticipated and feared sections.

The climb up Piton des Neiges, the island’s highest point at over 3,000 meters altitude, is one of the course’s highlights. The ascent is long, the air gets thinner, your legs burn. But at the top, the panoramic view of the entire island is a reward few other races in the world can offer.

The cirque of Salazie, with Hell-Bourg village and the Bébour-Bélouve primary forest, brings another dimension to the course. These dense, humid, lush tropical forests contrast with the volcanic zones crossed earlier. Each section of the Diagonale des Fous tells a different story of the intense island.

Reaching Saint-Denis after dozens of hours of effort is an emotionally powerful moment. The finish line truly means something here: you don’t just cross that line—you earn it.

What are the other races of the Grand Raid de La Réunion?

The Grand Raid de La Réunion isn’t limited to the Diagonale des Fous alone. The event includes several races, allowing a wide range of runners to experience the Reunion Island adventure in their own way: 

• The Trail de Bourbon, with its 106 km and over 6,000 meters of positive elevation, is designed for seasoned runners wanting to tackle a demanding ultra-trail without going to the extremes of the Diagonale.
• The Mascareignes, around 74 km, is a great introduction to long trails on the island.
• The Métis Trail, more accessible, opens up the competition to a broader public.
• Lastly, the Zembrocal Trail is a relay adventure for teams of four, covering a distance similar to that of the Diagonale des Fous, letting you experience it as a team.

This diversity of Grand Raid races is one of the event’s major strengths. Everyone can find their level of challenge, their pace, their way to explore La Réunion by trail.

Who are the iconic figures of the Diagonale des Fous?

The story of the Diagonale des Fous is also the story of its champions. Athletes who wrote their names in the legend of this grand raid through extraordinary performances and unwavering mental strength.

François d'Haene, a four-time winner, is one of the most iconic figures in the race. His ability to manage effort over such long durations and maintain impressive consistency on such technical terrains makes him an absolute reference in the world of ultra trail. Jean-Philippe Marie-Louise, also a four-time winner and local runner, embodies the deep connection between the island and its mythical race. For the women, Marcelle Puy holds the absolute record with five victories in the Diagonale, a feat that testifies to rare mastery over this unique course.

These athletes are not just champions. They are ambassadors of what trail running can produce at its best: perseverance, humility before the mountains, pushing oneself in the face of adversity.

How to prepare for the Diagonale des Fous?

Tackling the Diagonale des Fous is not something you do on a whim. Physical, mental, and logistical preparation must be conducted seriously, ideally over a period of at least six to nine months before the race.

Physically, your training should include regular long outings, specific work on climbing and technical descents, and gradually getting used to varied terrains. Muddy trails, rocks, roots—these are all surfaces you should get familiar with before finding yourself in the Reunion cirques. Strengthening your legs and core muscles is essential for endurance and protecting your joints on endless descents.

Nutrition and hydration management is another critical pillar of preparation. During an effort that can exceed thirty or forty hours for experienced runners, and up to sixty-six hours for the last finishers, you need a tried-and-tested nutrition strategy. Alternating between sweet and savory foods, managing aid stations, anticipating energy slumps… All that is learned and rehearsed in training.

Mental preparation is often the most underestimated aspect. The night, fatigue, pain, doubt... The Diagonale des Fous tests each runner in their deepest reserves. Learning how to get through these vulnerable moments and tap into your internal resources is an integral part of the adventure.

How to sign up for the Diagonale des Fous?

Entry to the Diagonale des Fous is subject to strict conditions, both to ensure the safety of participants and to preserve the spirit of the event. Demand is such that the lottery system has become nearly automatic for non-residents of La Réunion.

To be eligible, you must provide proof of sufficient performance, evidenced by recent qualifying races. The points system requires you to have finished several events, each granting a minimum number of points according to distance and elevation. Pre-registration is done on the official Grand Raid website, within a precise timeframe before the lottery date.

The waiting list is long and the selection is rigorous. But this also adds value to a Diagonale des Fous bib. Every runner who starts knows that they have earned their place.

For registered runners, the runner area on the official website provides all information related to the race, from participant lists to logistical details. The LiveTrail app, available as download iOS app and download Android app, allows real-time runner tracking, with splits at various checkpoints and live feeds from the course.

What is the unique atmosphere of the Diagonale des Fous?

Talking about the Diagonale des Fous without mentioning its atmosphere would be missing the point. The whole island of La Réunion comes alive during the Grand Raid. Locals line the trails, in the highland villages, along the roads… to cheer for every runner, whether they are leading the race or among the last to pass.

This human warmth is one of the most striking dimensions of the experience. In the cirques, isolated from the world, runners pass through hamlets where residents come out at night to offer a glass of water, shout encouragement, or light a lamp. Passing through these timeless places creates unforgettable moments of human connection.

The finish in Saint-Denis is an explosion of emotions. No matter your split time, no matter your place in the general classification. Crossing the finish line after dozens of hours of effort, cheered on by the Reunionese crowd, is a life-changing experience. The press and media presence on site attest to the magnitude of the event, which far exceeds sports and becomes a true societal phenomenon on the island.

The survival blanket you receive at the finish, the legendary t-shirt, tears mixed with sweat... all of this forms an unforgettable picture in the memory of every finisher. Recent editions have further amplified this emotional dimension, with more demanding routes, even more spectacular scenery, and a runner community ever more diverse, representing dozens of different nationalities.

What optical gear should you plan for running on the Reunion trails?

On the trails of La Réunion, your eyes face extreme conditions. The alternation between bright tropical sun, dark forest areas, cirque fog, and the slanting light of early morning creates particularly complex lighting situations. A suitable pair of glasses isn’t just an accessory: it’s a vital piece of safety equipment.

Photochromic lenses are especially suitable for this type of race. They automatically adapt to changes in lighting, so runners don’t have to change equipment mid-race, sometimes in tough conditions. On an ultra-trail that lasts dozens of hours and passes through drastically different environments, that adaptability is invaluable.

UV protection is also essential, especially during the high-altitude crossings along the ridges or at the summit of Piton des Neiges. The higher you go, the more intense the ultraviolet rays. Inadequate protection exposes your eyes to real risks, especially over such long durations. Our trail and running glasses are designed to meet these needs, with technical lenses that offer maximum protection and a secure fit, even in the most challenging conditions.

Comfort is another key criterion on such a long race. Frames that slip, foggy lenses, a stem that snags… on the Diagonale des Fous, every detail can make a difference. Runners with experience know: you don’t pick your optical gear lightly when you commit to this kind of challenge.

Key takeaways about the Diagonale des Fous

The Diagonale des Fous is a race like no other. It condenses into a few hundred kilometers everything trail running has to offer at its most beautiful and most demanding. Here are the essentials to remember:

• An ultra-trail of about 180 km with over 10,000 meters of positive elevation gain, crossing La Réunion from south to north;
• A course traversing unique environments: volcanic areas, the Mafate and Salazie cirques, primary forests, peaks above 3,000 meters;
• An event that brings together several races, from the Zembrocal Trail relay to the Trail de Bourbon, for all levels;
• An outstanding human atmosphere, fueled by the enthusiasm of La Réunion’s residents;
• Rigorous preparation is essential: physically, nutritionally, mentally, and in terms of gear;
• Entry subject to strict qualification criteria and a lottery for non-residents.

The Diagonale des Fous is adventure in its purest form. Preserved vision, peak performance: on Reunion’s trails as on any terrain that excites you, your gear is part of the story. Every run deserves the best you can bring with you.